The present invention is directed to a process for producing gold-chromium alloy from an electrodeposited gold on a chromium surface by heat diffusion.
The prior art methods heretofore utilized for gold plating a chromium surface require depassivating or acid treating the chromium surface so that the chromium surface is properly activated to subsequently accept a gold plate by electrodepositing gold over the activated chromium surface. Such a process is described in a recent U.S. Pat. No. 3,551,302 where good adhesion of a gold coating on chromium can be obtained by first cathodically treating the chromium with an activating solution, water rinsing, immersing in a mild acid and then gold plating. As indicated above, after the chromium surface is cathodically treated, it is dipped into an acid solution having a concentration of about 10% and is water rinsed prior to gold plating. Thereafter it is heat treated at temperatures between 200.degree. F. and 900.degree. F. to obtain a wear resistant finish.
In British Pat. No. 1,082,695 a process is described for the electrodeposition of gold onto a freshly depassivated chromium surface. However the patentee first points out that the chromium surface should be depassivated cathodically in a mild acid and then gold plated in a bath having a pH of between 2.5 and 4.5.